The Yale Mouse Metabolic Phenotyping Center (MMPC) brings together a multidisciplinary group of investigators at Yale to develop and apply novel in vivo and in vitro techniques to assess metabolic alterations in transgenic mice. The cornerstone of the Center is its Research Cores that will provide NIH funded scientists access to unique resources and standardized methods to characterize their transgenic mice. The Yale MMPC will consists of six cores; 1) the Administrative Core 2) the Animal Care Core 3) the In Vivo Metabolism Core, 4) the In Vitro Metabolism Core, 5) the Magnetic Resonance Spectroscopy (MRS)/Magnetic Resonance Imaging (MRI) Core, and 6) the Analytical Core. The Administrative Core will oversee the operation of the Center as well as the Pilot and Feasibility Project Program. The Animal Core will provide a centralized facility for coordinating receiving, screening and monitoring mice from investigators. The In Vivo Metabolism Core will perform glucose-insulin clamps using both radioactive and stable isotope technology to assess insulin action and energy metabolism in liver and skeletal muscle of awake mice. The MRS/MRI Core will perform noninvasive measurements of intracellular metabolites in muscle, liver and brain of transgenic mice using 13C/31P/1H MR spectroscopy as well as whole body measurement of fat and muscle tissue with MRI. The In Vitro Metabolism Core will perform phenotyping tests on isolated perfused organs (heart, liver, skeletal muscle, pancreatic beta cells) using both stable and radioactive tracer methodology in conjunction with GC/MS and NMR spectroscopic analysis. The Analytical Core will provide GC-MS and LC/MS/MS analysis of plasma and tissue samples obtained from protocols performed in the In Vivo, MRS/MRI and the In Vitro Metabolic Cores. Overall it is anticipated that the Yale MMPC will be a national research center that provides NIH funded investigators both inside and outside Yale access to unique, state-of-the-art, standardized methods to further characterize their novel transgenic and knockout mouse models of complex metabolic diseases.